UNIFY: one exe -- retire the pod/glass/steam compile split

The three build dirs (build\ pod, build-glass\, build-steam\) were compile-
time splits of the same game; the tax was real: a stale steam exe shipped 2
days behind, the felt keymap flipped with the boot flavor, and cockpit
clicks were silently dead in the pod build (the trigger-config incident).

Now everything compiles into the single build\ exe:
- CMakeLists: BT_GLASS/BT_STEAM options removed; the glass TUs (PadRIO,
  bindings, panel, glass windows, plasma) + FE/console + Steam transport
  compile unconditionally; both macros always defined (seam markers).
- Steam: steam_api.lib linked with /DELAYLOAD:steam_api.dll + delayimp --
  the DLL maps only when SteamAPI is first called, and every call site
  gates on BT_STEAM_NET=1 (BTSteamNet_* short-circuit on steamActive), so
  machines without the DLL run everything but Steam sessions.
- CABINET GUARD (btl4main): the miniconsole menu previously claimed any
  zero-arg launch -- unified, that would hijack the pod cabinet's boot
  shape.  The menu now requires BT_PLATFORM=glass (or BT_FE_MENU=1);
  platform parse moved above the fe_menu_mode computation.  A bare boot
  behaves exactly like the old pod build (DEV profile, wait for egg).
- Bats (play_solo/join/join_lan/play_steam) + the btoperator.py template:
  single build\ path + BT_PLATFORM=glass.  mkdist: one exe (+DLL scan
  picks up OpenAL32 + steam_api).  build-glass\/build-steam\/build-glass2\
  (a stale Jul-20 cache) deleted.

Verified matrix on the unified exe:
  bare zero-arg boot == old pod exe (same DEV profile + egg-load path;
    the segfault on a missing egg is pre-existing, baselined vs the zip exe)
  glass + BT_BTNTEST scripted click -> [cfgmap] ENTER/EXIT (trigger config)
  runs with steam_api.dll ABSENT (delay-load proven)
  glass zero-arg -> miniconsole menu
  2-node loopback MP: 145 ticks each, cross-connected
  BT_STEAM_NET=1 without Steam client -> "staying on Winsock", game runs

KB: context/glass-cockpit.md compile-gates section rewritten for the
unified model.

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

tools/mkdist.py

@@ -49,21 +49,15 @@ def main():
         ["git", "ls-files", "-z", "content/"]).decode().split("\0")
     tracked = [t for t in tracked if t]
 
-    exes = ["build/Release/btl4.exe", "build-glass/Release/btl4.exe"]
-    bats = ["players/play_solo.bat", "players/join.bat", "players/join_lan.bat"]
+    # ONE unified build (2026-07-21): every layer (pod game + glass cockpit +
+    # Steam transport) lives in the single exe; steam_api.dll is delay-loaded.
+    exes = ["build/Release/btl4.exe"]
+    bats = ["players/play_solo.bat", "players/join.bat", "players/join_lan.bat",
+            "players/play_steam.bat"]
     for p in exes + bats:
         if not os.path.exists(p):
             sys.exit("MISSING: %s -- build/refresh it first" % p)
 
-    # Steam build (EXPERIMENTAL): included when present -- play_steam.bat
-    # hosts/joins internet sessions through the Steam lobby (needs the Steam
-    # client running; steam_api.dll ships next to the exe).
-    if os.path.exists("build-steam/Release/btl4.exe"):
-        exes.append("build-steam/Release/btl4.exe")
-        bats.append("players/play_steam.bat")
-    else:
-        print("  (no build-steam -- play_steam.bat left out)")
-
     # Runtime DLLs living next to each exe (OpenAL32.dll etc.) -- the exe
     # fails to load without them (caught by the clean-extract boot test).
     for exe in list(exes):